\begin{tikzpicture}
	\tkzDefPoints{0/0/O, 2/0/A, 1.5/1.3/B, 1.2/1.8/C}
	\tkzDrawSegments(O,A  O,B  O,C)
	\tkzLabelPoints[left](O)
	\tkzLabelPoints[right](A, B, C)
\end{tikzpicture}

